Forge
Cards will need to be sacrificed in order to upgrade other cards. It is always preferable to sacrifice cards of the same realm as the card being upgraded (see Card XP Worth below). The amount of XP required to level a card depends on its star value and whether the card is an ally or essence card. The higher the star, the more XP is needed. Card Advancement - Allies Card advancement appears to follow an algorithm where upgrading a card to the next level (X+1) requires sacrificing X cards that give a constant (N) amount of XP. So you need to sacrifice 1 card, then 2 cards, then 3 cards, etc., for each subsequent level upgrade. The amount of XP the sacrificed card gives (N), changes depending on the star value of the card being upgraded. For eg., to upgrade a 1* card, you need to sacrifice 1, then 2, then 3, etc, cards that give 35 XP each (ie 1* cards) The formula for single step upgrade is b=Na, where 'b' is the amount of XP needed to upgrade a card by 1 level, for 1* cards N = 35, and 'a' is the current level of the card. So for 1* cards, b=35a The formula for cumulative amount of XP needed to upgrade a card from level 1 to level x is y=(1/2N)x^2-(1/2N)x, or for 1* cards, it is y = 17.5x^2 - 17.5x. The table below shows the formula for each star category of cards: The values below are estimates of the total amount of XP needed to upgrade a card from level 1 to the given level based on the above equations. These are estimates only, as it appears that the actual amount of XP needed to fully upgrade a card is slightly less than the expected amount. Tested values that match the theoretical values are shown with an asterisk (*). Tested values that are different from the theoretical values are shown in parenthesis. A 3-star ally needs 50614 XP to level from 1 to 40. 50605 may be sufficient. 50601 is likely insufficient. A 4-star ally needs 103943 XP to level from 1 to 50. 103915 may be sufficient. 103905 is likely insufficient. Card Advancement - Essence 3* essence cards (souls) are worth upgrading to lvl 8 requiring 1479 XP and returning an extra 2000 XP (or 2200 XP with realm bonus) netting 521 XP (or 721 XP with realm bonus) from the upgrade. 4* essence cards (savage souls) are multirealm cards. They are not worth upgrading except to lvl 2 using 85 XP and will return an extra 100 XP (net 15 XP - not worth the time). This will hopefully change as 4* essence cards are currently worse than 3* essence cards 1* (sprite) and 2* (spirit) essence cards are not worth upgrading before use. Although 2* spirits can be upgraded to lvl 2 using 44 XP and returning 50 XP (net 6 XP - not worth the time). Card XP Worth If the sacrificed card and the upgraded card have the same realm, a 10% exp bonus is applied. Currently, this bonus does NOT apply if the cards have more then 1 realm (Dragon Knight for example). If you sacrifice a card to another copy of that card, a bonus of 30% is applied instead of the realm bonus. Card stats improve per lvl